DSLR Scanning help

Hey guys. I am DSLR scanning using an Essential Film Holder (Both 35 and 120), but I am not 100% happy with the results. I don't feel that it is actually keeping the neg perfectly flat.
I am looking at other options, and one I wanted to try (as I want to also get sprocket holes scanned too) was to put the film in between 2 sheets of ANR or Anti Reflective glass. I was then going to lay it over the 120 mount of the essential film holder, and then scan that way. Has anyone tried scanning like this before?
I also know other systems are available but Negative Suppy and Valio are just out of my price range. There is one on Etsy called the lobster scanner that also looks quite good and uses magnets to keep the film in place, but cannot see many reviews on YouTube for it. I also do have access to a laser cutter and 3d printer, so have also looked at trying to design a holder that will keep the neg perfectly flat, without the need of glass.

For me getting a better scan first time and it taking a bit more time is more important than cranking out a roll of 36exp in less than a minute.

Thanks.